1. Field of the Invention
The present invention generally relates to an abrasive material for cleaning the needle point of a probe card and particularly relates to an abrasive material, which is capable of removing foreign matter adhering to the needle point of the probe card that is used to measure the electrical characteristics of a semiconductor chip formed on a semiconductor wafer.
2. Description of the Background Art
The probe of a probe card for measuring the electrical characteristics of a semiconductor chip formed on a semiconductor wafer is pressed against and contacted with the pad of the semiconductor chip. At this time, aluminum powder scraped from the pad of the semiconductor chip adheres to the tip (needle point) of the probe. If the aluminum powder is not removed from the needle point, aluminum remaining on the needle point is oxidized to aluminum oxide, allowing the resistance between the probe and the pad to be increased. Because the electrical contact is impaired, a continuity defect occurs so that the electrical characteristics cannot be exactly determined. For this, there are methods by which the needle point is cleaned every prescribed number of probes to remove the aluminum powder. The following methods are used to remove the aluminum powder.
(1) Methods using a grinding stone (see Japanese Patent Applications Laid-open No. 209896/1993, No. 96342/1992, and No. 2657/1988, and Japanese Utility Model Application No. 11167/1992). PA1 (2) Methods using a sanding plate (see Japanese Patent Applications Laid-open No. 166893/1993, No. 177849/1992, No. 105940/1991, No. 10176/1991, and No. 152034/1986, and Japanese Utility Model Application No. 26772/1995). PA1 (3) Methods using a ceramic plate (see Japanese Patent Applications Laid-open No. 4969/1986 and No. 282829/1989, Japanese Utility Model Application No. 55338/1986, Japanese Patent Applications Laid-open No. 2939/1990, No. 55835/1989, and No. 170933/1988). PA1 (4) A method using abrasive grains (Japanese Utility Model Application No. 97840/1986). PA1 (5) A method using a frosted glass (see Japanese Patent Application Laid-open No. 199141/1995). PA1 (6) A method using a glass coating (see Japanese Patent Application Laid-open No. 76242/1991). PA1 (1) The needle point breaks. PA1 (2) Aluminum powder adhering in clearance gaps cannot be removed because the intervals between the concave and convex parts of the surface of the ceramic plate are in the range of 1-12 .mu.m, while those of the needle point (contact surface) are 0.35 .mu.m approximately. PA1 (3) The needle point is worn down so that the life of the probe is short. PA1 (4) The shape of the needle point tends to be deformed under the same load (about 2.5 kgf) as in the probing operation. PA1 an abrasive layer including a layer of micro-powdered abrasive grains applied to a substrate, and PA1 a cushion layer having a buffer action and elasticity.
In these methods, the needle point is pressed against the pad in the same manner as in the probing operation to remove the aluminum powder.
However, there are the following problems in these methods.
Also, a method using a cleaning material in which micro-powdered abrasives are compounded in a base material is disclosed (see Japanese Patent Application Laid-open No. 244074/1995).
In this method, the cleaning material can prolong the life of the probe.
However, the above problems (1), (2), and (4) cannot be solved by the use of the cleaning material.
The present invention has been achieved in view of this situation and has an object of providing an abrasive material for the needle point of a probe card which is capable of effectively removing foreign matter adhering to the needle point of the probe, of avoiding damage to and deformation of the needle point, and of prolonging the life of the probe.